/*
 * factorial.c
 *
 *  Created on: Feb 23, 2012
 *      Author: Andrei
 */
#include <stdio.h>

int main(void)
{
	FILE *in;
	in=fopen("fact.in","r");
	FILE *out;
	out=fopen("fact.out","w");
	long n,p,k=0,cn;
	fscanf (in, "%d", &p);
	n=1;
	if (p==0)
		n=2;
	else while (k<p)
		{
			cn=n;
			while (n%5==0)
			{
				k=k+1;
				n=n/5;
			}
			n=cn+1;
		}
	if (k==p)
	{
		n=n-1;
		fprintf (out, "%d", n);
	}
	else if (k>p)
		fprintf (out, "-1");
	fclose(in);
	fclose(out);
	return 0;
}